The specificities of lectins for particular carbohydrate residues have led to their widespread use as tools in the characterization of complex carbohydrates and as probes for studying cell surface topography. Among their health related implications has been their use in blood typing, separation of populations of lymphocytes prior to bone marrow transplantation and various diagnostic assays. It is the long term objective of this research to obtain more information about the structures of lectins and their relationship to lectin function; such information should be valuable in allowing greater flexibility in the use of these tools as well as providing a better awareness of their limitations. This investigation will focus on the N-acetylgalactosamine specific lectins and will use the family of lectins from Dolichos biflorus as a model experimental system for exploring the relationship of structure to function in this class of lectins. The specific aims of this proposal are: 1) to continue the structural characterization of these lectins, including a comparison of their primary structures and the characterization of a newly discovered phosphorylated form of one of these lectins; 2) to continue studies of lectin function and the localization of active sites on these proteins; and 3) to initiate site specific mutagenesis studies in and effort to extend our understanding of structure-function relationships. A variety of biochemical methods including recombinant DNA technology, peptide fractionation, photoaffinity labelling and immunochemical procedures will be used in this study.